1. Field of the Invention
This invention relates to an adjustable torsion bar assembly used for pivoting one structure with respect to another. More particularly, it relates to a torsion spring assembly useful in moving a tip-up bed or the like between a horizontal using position and a vertical storage position.
2. Description of the Prior Art
U.S. Pat. No. 3,386,110 shows a tip-up bed pivotable mounted in a wall-type structure. U.S. Pat. No. 4,070,715 shows a combined bed and desk in which the bed frame is pivotable mounted at a rear end to a sidewall base with the bed in a vertical position being at an over center position. U.S. Pat. No. 4,318,195 is directed to a convertible furniture unit-bed and table/desk in which a parallelogram linkage is utilized with the point of pivoting of the bed at an overcenter position. Pivoting is provided (FIG. 5) by a pair of torsion bars variously fixed at opposite ends to the bed frame 12 and wall housing 18. Liftable bed weight in these devices include the frame, pivot attachments, mattress, covers and any connected furniture unit. As these bed elements change in weight the amount of force to raise the bed increases making it most difficult for a user to lift. In some instances it is necessary to provide a motorized lift unit. In any event, in most instances the pivoting mechanism must be custom built to adapt to the particular total weight of the total manufactured bed with its pivoting bed elements. Various manufacturers use different woods of various weights per volume or lumber of various sizes or particular designs in making bed frames or other parts of the furniture unit which contribute to the problem of having various total weights of the unit to be raised and lowered. Such custom building of pivot mechanisms adds much expense to the pivoting mechanism and results in an overall furniture unit of relatively high cost. Thus there has been a need for a low-cost, lightweight pivot assembly which functions satisfactorily, is easy to pull down and lift up by reason of less lift force being required, and is universally adaptable to bed or other constructions which are of varying weight.